Chapter 15: The Brian And Cranial Nerves Flashcards
Cerebrum consists of:
- right and left cerebral hemisphere ( 5 lobes)
Diencephalon consists of:
- epithalamus
- thalamus
- hypothalamus
Brain stem consists of:
- midbrain
- pons
- medulla oblongata
Grey matter
- houses motor and inter neuron cell bodies, dendrites, and unmyelinated axons
-Form the cerebral cortex (covers the surface of most of the adult brain) - form clusters within the white matter called cerebral nuclei
Features 5at support and protect the brain
- body cranium
- cranial meninges
- cerebrospinal fluid
- blood brain barrier
Cranial meninges
- continuous with the spinal meninges: the outer dura matter, arachnoid mater, and pia mater.
- has two layers fused together to enclose the dual venous sinus that drain venous blood from the brain and reliever it to the internal jugular veins
- no epidural space around the brain
Cranial dura septa contains:
- flax cerebri
- flax cerebelli
- tentorium cerebelli
- diaphragm sellae
Falx cerebri
Separates the two hemispheres at the cerebrum
Falx cerebelli
Separates the two hemispheres of the cerebellum
Tentorium cerebelli
Separates the cerebrum from the cerebellum
Diaphragm sallae
Form a “ roof” over the cells turcica of the sphenoid bone
Brain ventericles contain
- cavities within the brain that contain cerebrospinal fluid
- 4
Lateral ventricles are separated by
2
- seperated by a thin septum pellucidum
Third ventricle ( diencephalon)
- communicate with lateral ventricles through the inter-ventricular foramen
- communicates with the fourth ventricle through the cerebral aqueduct
Forth ventrical
Between the pond and the cerebellum
- merges with the central canal of the spinal cord
Cerebralspinal fluid
-Clear liquid that circulate in ventricle and subarachnoid space
- formed by choroid plexus
CSF functions
- buoyancy
- protection
- environmental stability: transport nutrient, helical, and removes waste from the brain
Choroid Plexus
- compromised of a thin layer of ependymal cells and capillaries that lie within the pia mater
- blood from capillaries is filtered from the CSF
Blood Brain Barrier
- regulates what substances can enter the interstitial fluid of the brain
- liquid solvable substance ( nicotine, alcohol, and anaesthetics)
- capillary endothelial cells, astrocytes per vascular feet, and continuous basement membrane contribute to the BBB
Where is the blood brain barrier reduced?
- choroid plexus
- hypothalamus
- pineal gland
Cerebrum
- “ seat of intelligence”
- centre of intelligence, reasoning, sensory perception, thought, memory, judgement, voluntary motor activities, and auditory activities
What does the cerebrum consist of?
- cerebral hemispheres
- cerebral cortex
- gyri
- fissures
- sulci
- corpus callosum
- basal nuclei
Gyri
Folds of the cerebrum
Fissures
Deep grooves in the cerebrum
Sulci
Shallow depressions in the cerebrum
Corpus callosum
Internally connects the right and left cerebral hemispheres
Lobes if the cerebrum
Frontal
Parietal
Temporal
Occipital
Central sulcus
Separate the frontal and parietal lobes
Precentral gyrus
The primary motor area of the cerebral cortex
Postcentral gyrus
Primary somatosensory area of the cerebral cortex
Lateral cerebral sulcus ( fissure)
Separates the frontal lobe and the temporal lobe
Parieto-occipital sulcus
Separates the parietal and occipital lobes
Frontal lobe functions
Voluntary movement, concentration, verbal communication, decision making, planning, and personality
Post central gyrus
Is a ridge in the parietal lobe immediately posterior to the central sulcus
Parietal lobe functions
Involved with general sensory perception
Ex. Shale and texture of objects
Temporal lobe
Involved in hearing and smelling
Occipital lobe
Processes incoming visual information and store visual memories
Insula
Deep to the lateral sulcus
Involved in interoceptive awareness, emotion, empathy, taste
Motor areas of the cerebrum
Control voluntary motor functions
Include:
- primary motor areas
- motor speech area ( Broca’s area)
Sensory areas of the cerebrum
Provide conscious awareness of sensation
Includes:
- primary somatosensory area
- primary visual area
- primary auditory area
- primary gustatory area
- primary olfactory area
Association area of the cerebrum
Interpretive, analyze, and store information
- somatosensory association area
- visual association area
- auditory association area
- wernickes area
- gnostic area
Primary motor area
- located in the precentral gyrus of the frontal lobe
- control voluntary skeletal muscle activity
Frontal Eye Feild
- located in the superior surface of the middle frontal gyrus
- regulate the eye movements for reading and coordinating binocular vision
Primary somatosensory cortex
- located in the post central gyrus area of the parietal lobe
- receives somatic information from touch, pain, itch, tickle, propreoception, thermal sensation, sensory receptors,
- locate the orgins of reception
Primary visual cortex
- located in the occipital lobe
- received and processes visual information
Primary auditory cortex
- located in the temporal lobe
- receives and processes auditory information
Primary gustatory cortex
- located in the post central gyrus in the parietal lobe
- processes and receives taster information
Primary oldfactory cortex
- located in the temporal lobe
- processes and receives smell information
Somatosensory association area
- located in the parietal lobe
- integrates and interprets sensations to determine the texture, shape, and pressure of the objects
Visual association area
- located in the occipital lobe
- processes visual information by analyzing clot, movement and form of an object
Auditory association area
- located in the temporal lobe
- allow to recognize a particular sound such as speech, music, or noise
Werkicke’s area
- located in the left hemisphere
- involved in recognizing, understanding and comprehending spoken or written language
Epithalmus contains
- pineal gland
-habenular nuclei
Pineal gland
Secretes melatonin
Functions of melatonin
- promotes sleepiness
- regulate circadian rhythm
Harbenular nuclei
Relay signals form the lambic system to the midbrain
- involved in visceral and emotions responses to odour
Thalamus
Serve as a relay station for reflexes and smell
Responsible for filtering out sounds and sights
Relay information to the somatosensory cortex
Infundibulum
Extends inferiority from the hypothalamus to attach to the pituitary gland
Hypothalamus functions
- control autonomic reflexes
- control endocrine system
- regulation of body temp
- control of emotions behaviours (pleasure, aggression, fear, rage, contentment, sex drive)
- control of food intake (vasopressin and aldosterone)
- regulation of circadian rhythms
Brain stem
Passageway for all tracts between the cerebrum and spinal cord
- contains autonomic and reflex centre
Contains:
- midbrain
- pons
- medulla oblongata
Cerebral aqueduct
Extend through the midbrain and connects the third and fourth ventricles
- surrounded by periaqueductal grey matter
Superior cerebellum peduncles
Connect the cerebellum to the midbrain
Red nuclei
Axons from the cerebellum and cerebral cortex form synapses in the red nuclei
- function with the cerebrum to coordinate muscular movements
Substantial nigra
Dopamine
- control subconscious muscle activities such as inhibiting forced involuntary activities
Parkinson’s disease
Loss of substantia nigra (dopamine) neurons
Midbrain nerves
- oculomotor (3): movement of the eyeball, change them shape of the lens
- trochlear(4): control the eyeball movement via thetrochlear nerves
Superior colliculi
- reflex centres for visual activity
- accommodation reflexes (tracking movements of the eyes, head and neck to respond to stimuli
Inferior colliculi
- part of the auditory reflex centre
-turns hard and eye towards an unexpected noise
Pons
- bridge that connects right and left sides of the cerebellum as well as to the rest of the brain
- helps control breathing
Ventral region of Pons
- pontine respiratory centre
- medullary respiratory centre
Helps control breathing
Dorsal region of pons
- ascending and defending tracts
- connect the left and right sides of the cerebellum
Pons nerves
CN5: Trigeminal nerve —> head and face
CN6: Abducens nerve —> eyeball movement
CN7: Facial nerve—> taste buds, salivary glands, and facial expressions
CN8: Vestibulocochlear nerve—> balance and equilibrium
Medulla Oblongata
Cardiovascular centre
- regulate heart rate and force
Vasomotor center
- cause the constriction of Arterioles led of elevates blood pressure
Other
- adjusts basic rhythm of breathing
- sneezing, swallowing, coughing, vomiting, and hiccuping
Inferior Oliver’s nucleus
Medulla oblongata
Relays impulses from proprioception to the cerebellum
Gracile and Cuneate nuclei
Medulla oblongata
Associated with the sensation of touch, pressure, vibrations, and proprioceptiom
Cranial nerves of the medulla oblongata
- CN8: vestibulocochlear
- CN9: Glossopharyngeal
-CN10: Vagus - CN11: accessory
- CN12: Hypoglossal
Cerebellum cortex
Consists of gray matter in a series of slender, parallel ridges called folia
Arbour vitae
Tracts of white matter in the cerebellum
Cerebellum nuclei
- grey matter
- axons carrying impulses from the cerebellum to the other brain centres and spinal cord
Vermis
Separates the two lobes of the cerebral hemispheres
Anterior and posterior lobe of the cerebellum
- govern conscious aspects of skeletal muscles
- makes all skilled and muscular activities possible
Cerebellum penduncles
- conduct impulses between the cerebellum and other part of the brain
Flocculonodular lobe
Contribute to equalibrium and balance
Limbic system
-“ emotional brain”
- controls emotions such as pain, pleasure, docility, affection, anger
- involved in socio- sexual behaviour
- involved in olfaction and memory
Damage to the limbic system causes
Memory impairment
Mixed nerves
Contain axons of both motor and sensory neurons
Review cranial nerves table
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